1. Technical Field of the Invention
The present invention relates to a data processing apparatus suitable for use in recording and reproducing of waveform data using a recording medium such as a hard disk.
2. Related Art
In Japanese Patent Laid-open Publication No. 2003-323174, a hard disk recorder is disclosed which is an apparatus for not only writing waveform data of multiple tracks recorded on a hard disk into a buffer memory for reproduction of the waveform data, but also recording waveform data written in the buffer memory on the hard disc. In this apparatus, track regions are respectively allocated to tracks constituting one piece of music (a song) in the buffer memory. Each track region consists of a plurality of buffer regions each having a memory capacity corresponding to one cluster. When reproduction of waveform data for one buffer region of one track is completed, the apparatus carries out reproduction of waveform data for another buffer region while transferring new waveform data from the hard disk to the former buffer region. Thus, the apparatus can reproduce a series of waveform data while continuously writing the waveform data.
In the technique of Japanese Patent Laid-open Publication No. 2003-323174, the contents of the music piece are specified by waveform data and song management data. Here, “song management data” defines one or more regions for which waveform data is actually reproduced, and respective reproduction timings for the regions. Accordingly, when it is necessary to edit a music piece through cutting or additing of a portion of a series of waveform data, the editing can be actually achieved by editing the song management data without editing the waveform data itself.
In the above-mentioned technique, however, transfer of new waveform data from the hard disk for each track region is carried out under the condition “reproduction of waveform data has been completed for one buffer region of the track region”. In a state where reproduction of waveform data has been completed for one buffer region of each of the track regions corresponding to a plurality of tracks, waveform data is transferred to respective track regions in a reproduction completion order. Such an operation incurs no problem if each track region has a sufficient number of samples, for which reproduction has not yet been completed. However, where the contents of the music piece are specified by waveform data and song management data, waveform data transferred to one buffer region may not be completely reproduced even when the amount of the transferred data may be actually within “one cluster”. Only a portion of the waveform data designated by the song management data is reproduced.
When there is a track with a very small reproduction region for waveform data not yet reproduced, the reproduction time of the waveform data is very short. For this reason, there is a possibility that transfer of subsequently-required waveform data may not be achieved within the reproduction time of the waveform data being reproduced. In order to avoid such a situation, it is necessary to frequently re-edit waveform data such that clusters having a very small reproduction region are eliminated, in the technique of Japanese Patent Laid-open Publication No. 2003-323174. However, such a task is very troublesome.
Although not specified in Japanese Patent Laid-open Publication No. 2003-323174, conventional hard disk recorders have a reproduction function referred to as “nudge”. This is a function for repeatedly loop-reproducing a short period (for example, 25 to 800 msec) of a loop part of a song. However, in the nudge function, when the loop part considerably approximates to an edge of the waveform data storing range in a buffer region (in detail, when the number of samples between the edge of the waveform data storing range in the buffer region and the center of the loop part is less than “½ cluster”), waveform data successive to the edge is transferred from the hard disk to the buffer region. Here, the loop part is settable only for samples already written in the buffer region. For this reason, when it is desired to greatly shift the position of the loop part, there may be a problem in operating the shift of the loop part because supplement of waveform data cannot be achieved within a given time.